Pie chart custom colours only show on hover

Hi,

I have found that when setting custom colours on a Pie chart (potentially other chart types) that the colours only show when hovering over them.
When no hovering they appear white, invisible on a white background.
This uses the same report as in ticket [T-014397], but just with added custom colours on the pie chart.
Ive attached a video to demonstrate.
We are on v4.0.11 Revision 41649.

Thanks.